摘要
Biodegradable wires,able to provide load-bearing support for various biomedical applications,are the novel trends in current biomaterial research.A thin 99.92%Mg wire with a diameter of 250μm was prepared via direct extrusion with an extreme reduction ratio of 1:576.The total imposed strain in a single processing step was 6.36.Extrusion was carried out at elevated temperatures in the range from 230 to 310℃and with various ram speeds ranging from^0.2 to^0.5 mm/s.The resulting wires show very good mechanical properties which vary with extrusion parameters.Maximum true tensile stress at room temperature reaches^228 MPa and ductility reaches^13%.The proposed single-step direct extrusion can be an effective method for the production of Mg wires in sufficient quantities for bioapplications.The fractographic analysis revealed that failure of the wires may be closely connected with inclusions(e.g.,Mg O particles).The results are essential for determining the optimal processing conditions of hot extrusion for thin Mg wire.The smaller grain size,as the outcome of the lower extrusion temperature,is identified as the main parameter affecting the tensile properties of the wires.
生物可降解丝可为各种生物医学应用提供承重支撑,是目前生物材料研究的新趋势。通过直接挤压制备出直径为250μm的99.92%镁丝,挤压比达1:576。单个加工步骤的总施加应变为6.36。挤压温度为230~310℃,挤压速度为0.2~0.5 mm/s。得到的金属丝具有良好的力学性能,其力学性能随挤压参数的变化而变化。室温下最大真拉应力可达228 MPa,塑性可达13%。结果表明,单步直接挤压法是一种有效的生产具有足够性能的生物医用镁丝的方法。断口分析表明,镁丝的失效可能与夹杂物(如MgO颗粒)密切相关。由于挤压温度低而导致的晶粒尺寸细小,是影响镁丝拉伸性能的主要参数。
基金
Financial support of the Czech Technical University in Prague in the frame of the project SGS18/191/OHK4/3T/14
financial support of the European Regional Development Fund (project CZ.02.1.01/0.0/0.0/16-019/0000778)
